Field of the Invention
Embodiments of the invention relate to the field of sputtering deposition technology, and in particular relates to a magnetron and a magnetron sputtering device.
Description of the Related Art
Physical vapor deposition technology or sputtering deposition technology, which generally refers to a thin-film preparation process employing a physical method to prepare a thin film, is a most widely used type of thin-film fabrication technology in the semiconductor industry. Physical vapor deposition technology is applicable to many process areas, such as copper interconnection technology, through-silicon via technology in the packaging field, and the like.
FIG. 1 is a schematic diagram of a structure of a conventional magnetron sputtering device. The device mainly includes: a process chamber 1, an electrostatic chuck 3 provided inside the process chamber 1 and used for bearing a substrate, a target material 2 and a magnetron 4 provided above the process chamber 1, and a magnetron driving motor 5. There is an air pumping device 13 attached onto a lower end or a sidewall of the process chamber 1. In a magnetron sputtering process, process gas (e.g., argon, or the like) used for generating plasma is fed into the process chamber 1, and under the combined effect of an electric field and a magnetic field inside the chamber, electrons are bounded by the magnetic field generated by the magnetron, the range of motion of the electrons is limited, and moving tracks of the electrons are elongated, which causes the electrons to be ionized to the greatest extent. A part of the ions react on a surface of the target material to form a compound, and another part of the ions, which are attracted by a negative voltage of the target material, bombard the surface of the target material 2, and cause a part of the atoms on the surface of the target material 2 to fall off and be deposited onto a surface of a substrate to be processed, thereby forming a desired film layer.
FIG. 2a is a radial cross-sectional diagram of a magnetron of the conventional art, and FIG. 2b is a target material corrosion curve of the target material corroded by the magnetron in FIG. 2a. Please refer to FIGS. 2a and 2b together. The magnetron includes an outer magnetic pole 102 and an inner magnetic pole 104, both of which have a spiral ring shape and are nested within each other, and in the outer magnetic pole 102 and the inner magnetic pole 104, magnets 108 with opposite polarities are uniformly distributed along the profiles of respective magnetic poles, to form a magnetic field that can bound plasma at a surface of the target material. Further, a constant gap 106 having a spiral ring shape is formed between the outer magnetic pole 102 and the inner magnetic pole 104. The constant gap 106 is used to define a region with a high density of plasma, which is adjacent to a front face of the target material, and form a closed current loop in the plasma to maintain the plasma. During the process, the magnetron performs a rotary scanning on the surface of the target material by taking an inner end 14 of the inner magnetic pole 104 as a center of rotation. The above magnetron is able to realize full target corrosion, and the utilization ratio of the target material is very high.
However, as illustrated in FIG. 2b, FIG. 2b is a target material corrosion curve of the target material corroded by the magnetron in FIG. 2a. It can be seen from the figure that a thickness of the thin film obtained by deposition employing the above magnetron has a poor uniformity. The reason is that: since particles sputtered from positions at different radii of the target material fly to the substrate at different angles, and specifically, an overall angle at which particles sputtered from a periphery of the target material arrive at the substrate is smaller than an overall angle at which particles sputtered from a center of the target material arrive at the substrate, causing the thin film deposited on the surface of the substrate to be thick in the center and thin on the periphery in its radial direction. The uniformity of the thickness of the entire film is greater than 3%, which is poor. Also, because of a relatively long path of a track formed by the gap 106, a relatively large glow voltage is required, and the relatively large glow voltage may cause damage to the surface of a P—GaN substrate in a subsequent ITO thin-film deposition process.
FIG. 2c is a radial cross-sectional diagram of another magnetron of the conventional art. As illustrated in FIG. 2c, the magnetron, with a shape similar to a kidney, includes an outer magnetic pole 62 and an inner magnetic pole 64 with opposite polarities to each other, and a gap 66 having a fixed width is formed therebetween. A track of such a kidney-shaped magnetron 60 does not completely cover a center of a target material (i.e., a center of rotation 14), and does not cover a periphery of the target material either, and thus cannot realize full target scanning. Also, the track of the magnetron defines substantially the same radians in a central region and a peripheral region of the target material, and thus for a short range sputtering, the problem that a deposited thin film is thick in the center and thin on the periphery will occur in the end.
In view of the above-described two types of defects in the conventional art, the question challenging those skilled in the art is: how to provide a magnetron capable of increasing the uniformity of the thickness of the thin film.